1. Field of the Invention
The present invention relates to a disc device for use in a personal computer or an audio apparatus and, more particularly, to a disc package in which different types of discs such as CD, CD-ROM, DVD and PD are loaded in a mixed fashion.
2. Description of the Related Art
As optical disc media, a diversity of types of discs have been proposed. Optical disc media based on bit modulation system include CD (Compact Disk), CD-ROM (CD Read-Only Memory), and CD-R (CD Rewritable) that permits one-time writing only. Optical disc media performing read/write operation based on phase change include PD (Power Disk), and optical disc media capable of magneto-optical reading/writing include MO (Magneto-Optical Memory) and HS (Hyper Storage). Available as a large-storage disc for handling audio, video and computer data are DVD-ROM (Digital Versatile Disk) of bit modulation system and DVD-RAM (DVD Random Access Memory) capable of phase-change reading/writing. Also available as a small disc for handling audio and computer data is MD (Mini Disk) capable of magneto-optical reading/writing.
As for disc devices for driving discs, there is available one type to which a single disc of any of the above types is loaded, and also available is another type of disc device, like a CD changer, which is loaded with a plurality of discs of the same type at a time and selects any of them when driving it.
There has been proposed a disc device type that is equipped with disc driving means capable of driving both a CD and a DVD with both the CD and DVD loaded.
Most of the disc devices compatible with different types of discs are loaded with a single CD or a single DVD and no consideration is given to the possibility of concurrently loading different types of discs therewithin. No consideration is given either to such a disc device that can be loaded with a combination of a read-only disc and a rewritable disc at a time, such as a combination of CD with DVD-ROM or DVD-RAM, or a combination of DVD-ROM and DVD-RAM. In view of diversification in the applications of optical disc media arising from requirement for a diversity of computer software and greater amount of data, there is a need for a disc device to which different types of discs are concurrently loaded.
The conventional disc device loaded with different types of discs such as CD and DVD determines the type of a disc with an optical head by reading TOC (table of content) data of the loaded disc, or by sensing the thickness difference between the cover surface of the disc and its recording surface or sensing the track density of the disc. For this reason, the device takes a long time from the loading of a disc to determining the type of the disc and finally to an actual reproducing operation of the disc.
As for a disc to which both a read-only disc such as a DVD-ROM disc and a rewritable disc such as a DVD-RAM are loaded, an error may take place in the determination of the disc type, and, for example, if the DVD-ROM is mistaken for DVD-RAM, recording laser power will be applied to the DVD-ROM, possibly leading a destruction of recorded data on the DVD-ROM.